Unit tests for alternate Git program (#30)

test/004_unit_git_program.bats

@@ -0,0 +1,67 @@
+load common
+T_YADM_CONFIG=; # populated by load_fixtures
+load_fixtures
+status=;output=; # populated by bats run()
+
+setup() {
+  destroy_tmp
+  make_parents "$T_YADM_CONFIG"
+}
+
+teardown() {
+  destroy_tmp
+}
+
+function configuration_test() {
+  # shellcheck source=/dev/null
+  YADM_TEST=1 source "$T_YADM"
+  # shellcheck disable=SC2034
+  YADM_CONFIG="$T_YADM_CONFIG"
+  status=0
+  { output=$( require_git ) && require_git; } || {
+    status=$?
+    true
+  }
+
+  echo -e "STATUS:$status\nGIT_PROGRAM:$GIT_PROGRAM\nOUTPUT:$output"
+
+}
+
+@test "Default git program" {
+  echo "
+    Default git program should be 'git'
+  "
+
+  configuration_test
+
+  [ "$status" == 0 ]
+  [ "$GIT_PROGRAM" = "git" ]
+}
+
+@test "Override git program (valid program)" {
+  echo "
+    Override git using yadm.git-program
+    Program should be 'cat'
+  "
+
+  git config --file="$T_YADM_CONFIG" "yadm.git-program" "cat"
+
+  configuration_test
+
+  [ "$status" == 0 ]
+  [ "$GIT_PROGRAM" = "cat" ]
+}
+
+@test "Override git program (invalid program)" {
+  echo "
+    Override git using yadm.git-program
+    Program should be 'badprogram'
+  "
+
+  git config --file="$T_YADM_CONFIG" "yadm.git-program" "badprogram"
+
+  configuration_test
+
+  [ "$status" == 1 ]
+  [[ "$output" =~ badprogram ]]
+}